Method and apparatus for gas chromatographic separation and determination of flue chtigen substances in a traegergas

摘要

1,188,776. Gas chromatography. SIEMENS A.G. 11 April, 1968 [14 April, 1967], No. 17713/68. Heading B1L. Gas chromatography column TS comprises two sections; the first (in the direction of flow) being surrounded by helical tube H, and the second being surrounded by concentric thermally conductive tubes Z and W and insulated with material I. The first section may be heated by means of heater B or cooled by coolant K which flows through helical tube H. The second section is heated in such a way as to produce a temperature gradient which decreases in the direction of flow; this may be produced by means of heater HK and cooling body KK, or alternatively by non-uniform electrical heater windings or by surrounding tube TS with a frusto-conical heater body whose apex points against the direction of flow. When coolant flows through tube H, the first section acts as a closed thermal gate to volatile material entrained in the carrier gas stream and none passes to the second section. When the first section is heated by heater B, the volatiles which have collected in the first section are evaporated and pass to the second section, whence they are separated by differential adsorption under the temperature gradient and emerge for detection as distinct bands.